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tomoyo: Add a kernel config option for fuzzing testing.

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syzbot is reporting kernel panic triggered by memory allocation fault
injection before loading TOMOYO's policy [1]. To make the fuzzing tests
useful, we need to assign a profile other than "disabled" (no-op) mode.
Therefore, let's allow syzbot to load TOMOYO's built-in policy for
"learning" mode using a kernel config option. This option must not be
enabled for kernels built for production system, for this option also
disables domain/program checks when modifying policy configuration via
/sys/kernel/security/tomoyo/ interface.

[1] https://syzkaller.appspot.com/bug?extid=29569ed06425fcf67a95

Reported-by: syzbot <syzbot+e1b8084e532b6ee7afab@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+29569ed06425fcf67a95@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+2ee3f8974c2e7dc69feb@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
This commit is contained in:
Tetsuo Handa 2019-04-12 20:04:54 +09:00 committed by James Morris
parent 1fb3b526df
commit e80b18599a
2 changed files with 22 additions and 1 deletions
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10
security/tomoyo/Kconfig
View File

@ -74,3 +74,13 @@ config SECURITY_TOMOYO_ACTIVATION_TRIGGER
You can override this setting via TOMOYO_trigger= kernel command line
option. For example, if you pass init=/bin/systemd option, you may
want to also pass TOMOYO_trigger=/bin/systemd option.
config SECURITY_TOMOYO_INSECURE_BUILTIN_SETTING
bool "Use insecure built-in settings for fuzzing tests."
default n
depends on SECURITY_TOMOYO
select SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
help
Enabling this option forces minimal built-in policy and disables
domain/program checks for run-time policy modifications. Please enable
this option only if this kernel is built for doing fuzzing tests.

13
security/tomoyo/common.c
View File

@ -940,7 +940,7 @@ static bool tomoyo_manager(void)
const char *exe;
const struct task_struct *task = current;
const struct tomoyo_path_info *domainname = tomoyo_domain()->domainname;
bool found = false;
bool found = IS_ENABLED(CONFIG_SECURITY_TOMOYO_INSECURE_BUILTIN_SETTING);
if (!tomoyo_policy_loaded)
return true;
@ -2810,6 +2810,16 @@ void tomoyo_check_profile(void)
*/
void __init tomoyo_load_builtin_policy(void)
{
#ifdef CONFIG_SECURITY_TOMOYO_INSECURE_BUILTIN_SETTING
static char tomoyo_builtin_profile[] __initdata =
"PROFILE_VERSION=20150505\n"
"0-CONFIG={ mode=learning grant_log=no reject_log=yes }\n";
static char tomoyo_builtin_exception_policy[] __initdata =
"aggregator proc:/self/exe /proc/self/exe\n";
static char tomoyo_builtin_domain_policy[] __initdata = "";
static char tomoyo_builtin_manager[] __initdata = "";
static char tomoyo_builtin_stat[] __initdata = "";
#else
/*
* This include file is manually created and contains built-in policy
* named "tomoyo_builtin_profile", "tomoyo_builtin_exception_policy",
@ -2817,6 +2827,7 @@ void __init tomoyo_load_builtin_policy(void)
* "tomoyo_builtin_stat" in the form of "static char [] __initdata".
*/
#include "builtin-policy.h"
#endif
u8 i;
const int idx = tomoyo_read_lock();